Conventionally, in an engine valve, a Co—Cr—W—C type material represented by Stellite® (including patent documents 1, 2) and a Co—Mo—Si type material represented by Tribaloy® (including patent documents 3 to 7) are used, and particularly Stellite is used in a member that demands an impact resistance.
The Co—Cr—W—C type material has an insufficient abrasion resistance though having a high toughness as a surface hardening material, so that the material cannot withstand use for a long period of time. Also, the Co—Mo—Si type material has an insufficient impact resistance though having a high abrasion resistance as a surface hardening material, so that problems such as cracks and exfoliation accompanied thereby are raised.